The clinical characteristics and natural history of 55 cases with antenatally diagnosed fetal uropathy were investigated. Percutaneous aspiration of the fetal pelvic or vesical urine was performed to decompress progressive unilateral hydronephrosis in 2 cases and to evaluate renal function in another 2 cases of bilateral hydronephrosis. As the postnatal diagnosis, upper urinary tract dilatation (hydronephrosis or hydronephroureter, 33 cases) and renal dysplasia (15 cases) made up 87% of all cases. A combination of hydronephrosis in one kidney and renal dysplasia in the other was also found in another 2 cases. Among 35 cases with upper urinary tract dilatation, 27 cases demonstrated pelviureteric junction stenosis and surgical intervention was necessary in 15 cases. In 17 cases with renal dysplasia, spontaneous regression was observed in only 3 cases and surgical intervention by means of percutaneous nephrostomy and nephrectomy was performed in 4 and 6 cases, respectively.